Undertale One Shots
by RAAM Is A Beast
Summary: This series is a mixture of one shots based upon head canons I have. I take prompts for this series. This series will include AUs (Mafiatale/Mobtale, Underswap, Underfell, Horrortale ect). Nothing belongs to me except from Aster (Error, Horror and Normal), Leo, Karma, Striker and Glenn. Psycho Vinnie belongs to a friend. I have permission to use him.
1. Lullaby

_**Prompt: No one else is home and Gaster is forced to sing a lullaby to put Magneto to sleep.**_

"See ya, Kid, G, K. Play nice, ya lil devil."

After Mafia Sans had warned his sometimes wayward pet to play nice, the others filtered through the funnel of a door, those who gave one wishing the lone shadow luck with the bouncing child currently occupied with the strange reptile christened Karma. To his credit, Karma loved the little ball of energy almost as much as he loved sleeping under the magically warm ribs of a certain Sans. Fetching the small metal ball after each admittedly pathetic (he was used to having to swim after it, give the water-lover some slack) fling, the creature would carry the ball back to the smiling, cheering, laughing, _annoying_ , tiny skeleton.

Moderate cracks stretched from each eye upwards and then down the tiny head, racing along the unblemished but not exactly smooth cranium and mandible to tease each other with connection at the base of the skull. Black magic swirled within a half-crescent moon plastered with a carefree smile. Every so often, a lilac tongue would spring forward like a jack-in-the-box, the child copying what he had witnessed an immature Sans (blasted Mafia and his devil-may-care attitude) do. Each blink hid away mini lilac eyes, a mixture of the shadow's darker purple and the true mother's lighter cyan ones.

"Dad, what's a 'stag do'?"

Childishly high and unusually sparky, the infinitesimal skeleton's voice was hard to not aw at and make cute gestures. Unless you were immune, like Gaster. Said Gaster glanced sideways, schooling his bones to show interest when all he wanted was to get his paperwork done. This free night - no one else but the one year old in his vicinity - was the older skeleton's to take and mold into whatever he wished with it. His younger brother - Aster - would not be surprised if answering the curious child was not on that temporary bucket list. With a mental scowl, Gaster could just hear his sibling mock him for the misfortune of a child being naturally curious.

"Where did you hear it from?"

Monotonous, bored-sounding, the skeleton's voice wasn't one many would willingly listen to, if you could help it. He reminded many of their boring history or english teachers from secondary school. All words and no personal expression. His neutral, blank face did not help in removing that comparison.

A little, cu- no. Not that word. But a little giggle reached his ears as the skeleton child clambered gracelessly onto his cloaked lap.

"Auntie Fell said that they were off to Leo's stag do tonight and that you weren't invited because you're rude and socially... aw... aw... aw..."

"Awkward."

"Socially awkward. What is that also?"

He sighed, placing the uncapped pen down, only to flick a non-existent eyebrow - well, eye ridge - up in exasperation as the kid stole the pen from his desk and failed at getting it into his pen pot. The adult grasped the pen with a helping hand and dropped it into the pot while his true hands were occupied with making sure the excitable child did not flop off his legs. As curious as he was, sleep flashed within lilac eyes.

"A stag do is a party where the male mate is taken out by his friends as a congratulations for his upcoming marriage. Socially awkward is where a person is too shy to go into social situations."

The cloaked - lilac to match his eyes - skeleton was silent for a minute before he decided to break the pleasant silence. Again.

"You're not socially awkward. You're just a mean old man."

Giggles followed this statement, quiet from tiredness. Believing the child to go to sleep, Gaster let the kid lay against his ribcage, clothed in a pitch black cloak not unlike the midget one covering up the tiny one.

"So, dad, what are you... doing?"

Within that sentence, the small one yawned and the adult monster sighed with a frustrated tone. Was he not going to get a break tonight? Judging by the squirming, no, he was not. Gaster scowled, consciously checking around the room and casting his magic around the house to see if he was truly alone before scooping up his charge and softly murmuring to his child, protected within his encompassing arms.

Even in singing, his voice didn't loose the monotone. It did soften, however, masking the plain component with splashes of affection. Gaster would rather die than admit anything stronger than affection. Deep within his upside down grey soul, an abstract noun referred to as 'love' blossomed with each syllable he intoned to his child. His Magneto.

"Day is done,

Gone the sun,

From the lake, from the hills, from the sky.

All is well, safely rest,

God is nigh."

A smirk, satisfied, loved and affectionate back, curled the black mouth of Magneto through the gleaming bone as the child settled as his father repeated the same lullaby - Magneto's favourite, he'll have you know - with a gentle swaying of his arms.

Hours later, the group returned from their night out, pleasantly buzzed but not absolutely drunk. Pictures were taken and knowing looks cast around when they laid their eyes on the teasing material of the usually awake Gaster asleep with Magneto encased by a father's arms. Aster murmured two words to the air, where Leo and the werewolf called Psycho Vinnie, Psycho or PV for short, stood.

"Cough up."


	2. Defenders

**Prompt: Someone hurts Psycho and Mafia Sans and Karma and Striker get triggered.**

 _Prompt Extension: Psycho gets hurt, Mafia Sans defends him, takes the hit and Karma gets triggered._

The day had started like any other, a fluffy-tailed white Neko annoying the werewolf of the group with said fluffy tail. It was a beautiful thing, but it was too easy to tickle passersby with as the cat lay across a shelf he had been forbade to go on. It wasn't the best thing to wake up to in the morning, a face full of white fur as you walked down the steps.

"Leo! Get off the shelf!"

Giggling with barely repressed glee, the cat slipped down from the shelf, prancing away from the ruffled skeleton who's face had been bombarded by fur. Said skeleton, brushing the long threads of fur from his black cloak with a frustrated grimace on his face. Why did he agree to join them in the house?

As the Neko terrorised (oh, so scared) the house with his bushy tail, the werewolf of the house was wisely sat outside on a smooth log, stripped of its protective bark. There had been bark upon the trunk, until Striker came along and rubbed it all off with his insistent side itches.

Striker was no normal creature, like Karma was no normal lizard thing. Thirteen feet tall with twenty two feet of length and weighing around 1800 pounds, you did not want him to decide your legs needed snapping. As it was, the head of the monstrosity was next to the werewolf, two pairs out of the four closed in contentment. The remaining two stared wherever they stared. Psycho was nor close enough to determine exactly where the gaze settled.

White irises and pupils meant that it was extremely hard to tell if you had the beast's attention, but, lucky for Psycho (or unlucky if Striker tries to lay on him), he almost always had his attention.

Idly musing about the large growth the male had forced his body to go through, he faintly remembered that it was Psycho's disappearance which had caused it. And, if Gaster was to be believed, Striker was a Paladin Netik. A guard to a Queen, if you will.

Slime dripped and pulled the man from his thoughts, coating his shoulder with the viscous, black fluid. Glancing at the creature, he saw that its green tinted - in certain lights - head was watching many of their house mates leave via teleportation. Work, play, companionship. Psycho had neither at this moment in time.

As if sensing his abysmal thoughts, the giant beside him carefully butted a slimy head against his back, throat rumbling with the purr of an engine. Grudgingly, Psycho stroked the muzzle of the Paladin. Maybe he had one.

Some time passed, the werewolf and his devoted Netik settled in the shade of the trees, a natural bench their place of rest. During this time, the great lump of muscle had moved away from the log and slipped into the sea nearby. Graceful and beautiful, the creature glided beneath the water while it's small audience watched.

A twig snapped, the only thing preceding sudden pain and burning to twist the flesh on Psycho's right shoulder, a blast of sound from a sniper echoing into the house via an open window.

Karma, as much as a little devil he was, could tell that the sound did not bode well and promptly jumped onto the nearest and only living thing in the house. A sleeping, content Mafia Sans.

Shrieking into where his ear should be was a surefire way to jump start the skeleton, especially just after pouncing urgently upon his ribcage.

"Urg! K. Wha' tha hell?"

The skeleton grunted, annoyed by the very rude awakening. Karma squeaked apologetically before making mewing sounds and trying to get Mafia to follow. Unfortunately, he could be dense at times, and now was one of them.

Right on cue, a second gun shot rang out, closely followed by angered, demonic, powerful screeches from the largest occupant of the house and the island the house had been built upon. Spending just a second to marvel at the pulsing tones of the piercing cry, Mafia Sans unholstered his trusted Colt 1908 Pocket Hammerless and leaped up from the sofa, barging through impolitely closed doors and bursting out onto the small concrete pathway, leading to the adjacent beach.

The scene which greeted the monster clad in a crisp, dapper, brown suit straight from the wardrobe of a 1930s mob boss took shape like this.

Blood splattered across the small grains of eroded rocks, no pattern nor owner. There was too much to be just the werewolf's, and some of it was dark blue clumped with the black slime only found on the local Netik, who was tearing into a human with large teeth and taloned hands. His secondary pair of arms twitched with the urge to disembowel his prey. Common sense told the beast to think better, for a sniper flopped within one twitching hand.

The second thing to become apparent was that Bulldog was nestled against a tree trunk, holding his hand to his right shoulder, where red stained his long sleeved shirt. On the ground nearby, a soiled silver bullet sparkled with fake innocence.

And the last thing to be noticed was the flash of a scope in the sun before pain stunned Mafia Sans and blinded him with the physical feeling of obliterated bones around his fragile monster soul. A second, agonizing bullet crushed his firing hand, leaving the skeleton vulnerable.

Or so the remaining human thought.

"K..."

Mustering up the last of his energy, the short monster clicked his middle finger and index finger together, commanding the small but deadly organism to attack with all of his vast might.

He did not see his companion valiantly defend his unconscious body, at the cost of getting shot himself. Either way, he would have been proud.

A few days later, Mafia Sans awoke on his couch, Karma dozing protectively over his soul, his front leg covered by a cast. On that cast were the words:

' _ **Thank you.**_ '

Two initials scrawled after the words made Mafia Sans cock and eye ridge in disbelief and appreciation.

' _ **PV**_ '


	3. Not Lost Anymore (Dialogue Version)

THIS... HURTS...

I AM TRAPPED.

I AM LOST.

I AM NO WHERE, NO ONE.

I AM...

I... AM...

LOST.

I AM LOST.

* * *

LONELY.

THIS PATHETIC EXISTENCE IS LONELY.

I AM LONELY.

WHY WILL IT NOT END?

WHY DID THE CORE MAKE ME INTO THIS... GHOST... THIS SHADOW OF MYSELF?

I MISS MY BROTHER.

DOES HE MISS ME TOO?

* * *

THIS IS TORTURE.

THIS IS DEATH.

WHERE IS HE?

WHERE IS MY BROTHER?

I SHOULD SURELY SEE HIM, FOR HE IS DEAD TOO.

* * *

ASTER!

WHERE ARE YOU?

I AM SORRY...

PLEASE... COME TO ME... BROTHER...

I DO NOT WANT TO BE ALONE ANYMORE.

* * *

WHAT IS THIS?

A LIGHT?

I MUST GO TO IT, TO SEE WHAT IS SHINING HERE.

WH-WHERE AM I?

 _Brother. Welcome home._

ASTER?

NO! DON'T LEAVE ME!

...

...

ANOTHER STUPID DREAM.

HE WILL NEVER COME.

ASTER IS DEAD.

I AM NOT.

* * *

IT HAS BEEN YEARS.

NO ONE WILL COME.

I AM FORGOTTEN.

I AM WINGDING GASTER.

 _And I am Wingding Aster. It has been a while, dear brother._

ASTER?...

 _Gaster. Come, brother. We can go home now._

WHY DID YOU WAIT SO LONG?

 _I had to make sure our home was perfect, brother._

 _Welcome home, Gaster._


	4. Why Do You Taste Like Roses?

**Prompt: Horror Sans is wasted and kisses Mafia Sans.**

 _Horrortale and Mobtale/Mafiatale Sans do not belong to me. I would appreciate it if someone could tell me who they belong to._

 _Leo and Glenn (Mentioned), Karma (Mentioned) and Alexander (Mentioned) belong to me._

 _Vinnie and Psycho Vinnie belong to a friend._

* * *

It had been a long, long, long, _long_ night. And, he checked the nondescript watch clutching his bones for a wrist, it had only been two hours. Two hours... Mafia Sans was trapped with Horror Sans (Redeye), Leo (Kit), Vinnie (V) and Psycho Vinnie (Bulldog) for another five hours. _Five_.

Leo ("Wha' a' ya doin', Kit?"), the mischievous little fur ball, had decided it would be within his questionable ideas for fun to take advantage of Vinnie's tipsiness to dance. His fiancé, Alexander, also a Neko and a deep fox red with small black rings at the end of his tail, was on a business trip. This often caused the smaller male to become bored and lonely, which was where Vinnie stepped in as a close friend.

Knowing each other for nine years really did that to people. Built bridges between people. And species. It was cute, to be honest.

But... Horror Sans was quickly reaching his drinking limit, slurping down his irresponsible shots of jagermeister and immaturely winking at the other Sans from behind the werewolf's back as he twirled his index finger around the band marking him as married. The lucky bugger - unlucky in this case as the werewolf was on the sadistic side - was sunning himself in California with Alexander and Karma.

K. That little, water-loving, six-legged devil. Mafia Sans missed his unruly friend, his crazy and protective attitude, his way of flicking all of the water _from_ a full bath tub and drench the Sans and anyone else in the room, his weird obsession with ripping up light coloured cloth but storing black or dark coloured ones, his every little unique quirk.

A small smile quirked up the corner of the Sans's mouth as he landed on an instance where Karma had destroyed one of Glenn's (Chihuahua) bright blue shirts as he had donned it. Apparently it had been his fav-

"Oi. Druggie."

Raspy and deep, the slurred tone of the other skeleton begged for attention to be paid. Huffing, Mafia Sans spun on his chair to face Horror Sans, his most likely rude reply muffled by chipped, hard and unforgiving teeth meeting his, parting to allow a crimson tongue to invade the open mouth of his unwilling partner.

When he was free again, all Mafia Sans could get out past the barricade of shock was:

"Why tha hell do ya tas' like roses?!"


	5. Cannon Fire

**Prompt: Muffet puts on a circus show with her spiders and asks Frisk to be in the grand finale as a human cannonball. - Barbacar**

 _Requested Headcanons: Muffet is almost never seen without a huge, tremendously fat purple cigar in her mouth, made from spiders and webbing. The smoke from it is purple and smells like a bakery. Frisk often lights it for her with a lighter they keep in their pocket._

 _Muffet often swallows people whole, intentionally or accidentally. She spits them out eventually, though._

 _When Muffet's silky black hair isn't tied up in pigtails, it's long enough to reach her waist._

 _Muffet's title is Princess of the Spiders._

 _Muffet, Frisk, Mettaton (Mentioned) and Sans (Mentioned) belong to Toby Fox._

 _The Muffet head canons belong to Barbacar._

* * *

A mop of brown hair bounced with each excited step as the human carried some equipment and followed in the trail of a spider coated in a purple dress, complete with a wonderfully tied set of laces at the back of the dress. These laces sewed the back of the dress closed and ended in a small, pretty bow near the top.

Frisk smiled as they gazed at their handiwork, having helped the spider to get properly dressed. Even they had changed into something much more oriental and beautiful for the day.

Today the entire underground would have some entertainment, other than the ghost in a robot suit, Mettaton. Frisk wasn't saying he was bad - she enjoyed hanging out with the celebrity - but some variety now and then helped.

Skipping down the road, the human smiled at each person they passed, full to the brim with excitement. This would be their first, and most likely not the last, time.

A poster blared to the left and the human tilted their head to look at it as they walked past. It advertised their spider circus, complete with a stunt cannon for the finale. Seeing the big, imposing, purple cannon sent a flare of nervousness around Frisk's belly. A white star twinkled at them from the poster, as if to assure them all would be well.

It was to take place in the medium climate zone, Waterfall. Not too hot, not too cold. Perfect for a large gathering of bustling monsters and single human alike.

Helpful monsters pitched in the effort to set up the circus, rewarded with a thank you from Muffet, black hair swaying down to her waist and moving with each slight change in her head's position.

When the set up was complete, the show began. Spiders danced, jumped through rings burdened with flames, told jokes and even made a pyramid upon Muffet's head without being accidentally eaten.

Surprisingly, they were also not burnt by the bulky cigar puffing out the smells of a bakery and enticing nearby stomachs to rumble in blissful memory of the Princess of the Spiders' baking.

But all of the acts passed too soon for the butterflies in Frisk's stomach, fluttering and tickling in a nauseating pattern. They fastened on their helmet and shrugged on a plump lilac jacket, taking deep breaths to try and relax.

"Are you ready, my dear?"

The hiss of their adopted mother asking the simple question only served to make what will happen all the more daunting.

But, Frisk thought with determination, they would do this because Muffet wanted them to.

The stunt cannon seemed to gleam at them, gloating its superior strength and size as the tiny human slowly clambered from one step to the other, hauling themselves into the barrel of the canon.

"And now for the final act!"

Muffet announced, plumes of purple smoke floating around her as the spider used a pair of arms to light a match and in turn light the cannon.

Seconds lengthened to hours, seemingly, as the human lay on their belly waiting to be shot out and up. The lit fuse disappeared into the cannon before it made a loud pop and Frisk was ejected from the shaft to land...

In front of the cannon.

They looked around, seeing the crowd laugh - in a good way -, hold a hand to their souls in relief that it was a practical joke and some even smiled at Muffet for not shooting the fragile child from an actual stunt cannon.

Later on, Frisk found out that they had meant to fly and that Sans had messed with the cannon and made it his own practical joke out of a circus.


End file.
